The invention relates to a corrosion-protected modular unit with two components, of which a first metallic component exhibits a socket opening, into which a second component is capable of being inserted at least partially, and the second component has a sealing element which interacts via an abutment face with the surface of the first component.
Metallic components have to meet growing demands not only with regard to higher load-bearing capacity but also with regard to longer service life. To this end, anticorrosive measures in particular are of crucial importance. But it is a disadvantage that with increasing effort in respect of protection against corrosion the production costs also increase. In order to eliminate this disadvantage in obvious manner it is known from the modern automobile industry, for example, to provide metallic blanks with a coating, such as a lacquer film that is capable of providing protection against corrosion, before they are supplied to a further processing stage. However, disadvantages with respect to the tolerances of the components arise as a result of the application of a lacquer film of this type. Accordingly, in working procedures that are, in part, elaborate, the lacquer film subsequently has to be removed at contact-pairing points and from bores before a connection to other components can be made. By virtue of the remachining of the metallic components the lacquer film is partially removed, resulting once again in a surface of attack for corrosive media.
Another possibility for preventing the surface protection from totally covering the entire. component consists in machining, in advance, those parts of the component to be treated with surface protection, then in covering them, sealing them or closing them off with adhesive, in order finally to be able to apply the surface protection. In this case the covering isxe2x80x94for the most partxe2x80x94removed and cannot be used again. However, this known method is very elaborate and therefore cost-intensive
The technical problem underlying the invention is to create a modular unit comprising two components that enables optimal protection against corrosion with simple, cost effective means. In addition, a process for producing a corrosion-protected modular unit is also provided.
In accordance with the invention, a first metallic component exhibits a socket opening, into which a second component is capable of being inserted at least partially. For the purpose of sealing the components that are mobile relative to one another the second component is endowed with a sealing element. An abutment face which is formed on the sealing element interacts with the surface of the first component. According to the invention, the first component is a metallic blank which, for reasons of protection against corrosion, is simply and cost effectively coated with a lacquer film or is provided with a surface protection in another manner known as such. The necessity to abide by exact dimensional tolerances was complied with by a mechanical removal of the lacquer film or of the surface-treated regions being effected in respect of the first component. On this machined region a contact pairing with a second component is subsequently possible. The second component may, in turn, be composed of several individual parts. To the extent that they are mobile relative to one another, these parts should be protected by a sealing element against the penetration of corrosive media between the moving parts.
In accordance with the invention, it is proposed to apply an anticorrosive element onto the surface of the first component in firmly adherent manner between the abutment face of the sealing element and the surface of the first component.
In this connection, an adhesively bonded packing, washer or film may serve as anticorrosive element. Of course, the surface of the first component has to be freed of dust, grease and other impurities prior to connection to the anticorrosive element. Tie anticorrosive elements may be manufactured from a variety of materials, depending on the field of application of the components. The use of polyvinyl chloride (PVC) has proved to be particularly advantageous. This material is resistant to water and also to heat, cold, oil and grease. It exhibits advantageous flexibility over a wide range of application and, in addition, is outstandingly suitable for adhesion bonding. Furthermore, PVC is available in the form of self-adhesive film.
Since the mechanical erosion of the surface-treated region of the first component is carried out, for the most part, in relatively liberal manner, and since the anticorrosive element is to cover the surface-treated region completely, it follows that the abutment face of the sealing element has a smaller geometrical external dimension than the external dimension of the anticorrosive element. But this represents a certain excess length of the anticorrosive element beyond the abutment face of the sealing element. As a consequence of the pairing of materials for sealing element and anticorrosive element, a slide surface results which makes an additional sealing effect possible. Here a complementary profiling would even be conceivable, creating a type of labyrinth seal.
A special application according to the invention will be elucidated in the following on the basis of a modular wheel-carrier unit pertaining to a motor vehicle. The first component is the wheel-carrier of the motor vehicle 5 and the second component is the ball pivot of a ball-and-socket joint. The ball-and-socket joint consists, in turn, of a housing and a bearing bush which is received in the housing and in which the joint ball of a ball pivot which is supported so as to be universally mobile is inserted. A ball-and-socket joint of this type further exhibits a bellows-type seal by way of sealing element, which is in sealing contact, on the one hand, with the housing and, on the other hand, with the ball pivot and which consequently seals the components that are mobile relative to one another in relation to environmental influences. On the side facing towards the wheel-carrier the bellows-type seal is provided with an abutment face which interacts with the surface of the wheel-carrier. As a blank, the wheel-carrier is provided, in the manner previously described, with a surface protection which may consist of a lacquer coating, for example. Since the conical pivot region of the ball pivot of the ball-and-socket joint has to be inserted in accurately fitting manner in the socket of the wheel-carrier which is provided for it, prior to mounting of the ball pivot it is necessary to remove the extraneous substances which have inadvertently penetrated into the socket. In order to obtain an optimal sealing of the overall system it is furthermore necessary to machine the abutment face of the bellows-type seal on the wheel-carrier. The surface of the wheel-carrier must be plane, in order to achieve an optimal sealing effect. In accordance with the invention, an anticorrosive element is adhesively bonded onto this premachined surface of the wheel-carrier, the outside diameter of said anticorrosive element being larger than the abutment face of the bellowstype seal. In order to enable dimensionally accurate fixing of the anticorrosive element, firstly a mounting pin is inserted into the socket opening and subsequently the anticorrosive element is adhesively bonded onto the surface region of the wheel-carrier, with simultaneous positioning of the anticorrosive element. After the mounting pin has been removed, the ball pivot of the ball-and-socket joint can, be inserted into the socket which has been prepared for it and can be fixed to the wheel-carrier in a manner known as such, for example by means of a screwed connection. During the fastening of the ball pivot to the wheel-carrier the bellows-type seal undergoes a slight elastic deformation in the axial direction, so that it interacts, subject to elastic bias, with the surface of the wheelcarrier. Consequently an optimal sealing effect is obtained.
With a corrosion-protected modular unit according to the invention and with the process that has been developed for this purpose an optimal resistance to corrosion of two components that are to be sealed in relation to one another is obtained. Creep corrosion of the sealing element is totally prevented. As a consequence of the machining of the surfaces, areas of surface roughness can be avoided which would otherwise be favorable for creep corrosion. Overall, an increase in the service life of metallic components is obtained by this means. In addition, a cost effective variant has been discovered that also enables integration into series products that are already in production.
A preferred embodiment variant of a corrosion-protected modular unit according to the invention will be elucidated in greater detail in the following on the basis of the drawing. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.